The invention relates to a composite section having a section or part of the rail cross-section made of light metal and also, mounted securely on the same, a section made of a heavy metal which forms a part of the outer surface of the composite section--in particular a composite conductor rail of aluminum or an aluminum alloy and a steel facing or insert joint to it by means of extrusion.
The power supply for electric trains is made both via steel conductor rails and with composite conductor rails which are either made up of steel and aluminum parts that are screwed together or joined by washer-locked bolts or are extruded out of these materials. In another version aluminum has been cast into the sides of a steel I-beam and subsequently cold rolled. Finally it is also state of the art to make a composite section by clamping a stainless steel sheet onto an aluminum section.
The standard steel/aluminum composite rails for electric train networks suffer several disadvantages. The steel I-beam section with cast-in aluminum is just as undesireable because of its excessive weight as are the conductor rails of steel and aluminum sections that are screwed or bolted together with locking washers; in all cases only a small part of the steel I-beam are used viz., the head which is used for its wear resistance.
In the case of aluminum composite rails with clamped on stainless steel parts the thickness of the stainless steel sheet is, due to the manufacturing method, limited to 2 to 3 mm. Such conductor rails are therefore suitable only for cabin taxis and People-Movers in which there is no great demand for wear resistance. Their use in underground and rapid transit railways is out of the question.
Co-extruded steel/aluminum conductor rails can indeed be manufactured with steel facings twice as thick as the above mentioned rails with clamped on stainless steel sheet, and this without greatly increasing the weight. However, for underground railways which are very demanding with more than 1.5 million collector shoe passes per year, such a steel plate is too thin as a wear resistant facing. This is true in particular for old railway networks with relatively large tolerances where the current collectors mounted on the power unit can wear the conductor rail on one side.
In view of the above the object of the present invention is to devleop a composite section, in particular a high performance composite conductor rail which is able to meet the greatly increased requirements of underground and rapid transit railway services and, along with high electrical conductivity and low weight, offers a sufficiently thick wear resistant facing that the composite section is assured to provide an adequate service life even under the hardest and least favourable operating conditions.
It also lies within the scope of the invention to replace or render superfluous conventional parts of conductor rail networks such as supports and clamps by providing an appropriate shape of conductor rails cross-section.